Conventional ultraviolet pasteurizers for sterilizing an indoor space comprise an ultraviolet lamp that is energized to emit ultraviolet radiation to sterilize indoor walls and indoor air. The ultraviolet pasteurizers are basically classified into two types, i.e., one for applying ultraviolet radiation to indoor walls or the like and one for emitting ultraviolet radiation in a tubular member to sterilize indoor air that flows through the tubular member.
The former type of ultraviolet pasteurizer is disadvantageous in that since direct exposure to ultraviolet radiation is harmful to persons, no entry into the room is permitted while the ultraviolet pasteurizer is in operation or the application of ultraviolet radiation toward any person in the room needs to be inhibited.
The latter type of ultraviolet pasteurizer is also problematic in that it can sterilize microorganisms suspended in the air, but is unable to sterilize microorganisms attached to wall, ceiling, and floor surfaces.
It is therefore an object of the present invention to provide an improved ultraviolet pasteurizer which can be operated in different modes depending on whether there is a person in a room to be sterilized or not, for thereby solving the above problems.